Dynamische Küste des Nildeltas
Background
The coastline at the Nile mouth near Alexandria is defined mainly by the balance of sediment deposition by the Nile River and its removal by the Mediterranean Sea.
The sediment load of the Nile River was significantly reduced by the Aswan High Dam located about 1000 km upstream, which was completed in 1970. Before the construction of the dam, the Nile Delta received an annual sediment load of approximately 130 million tons. Today, this figure has dwindled to around 16-20 million tons, leading to reduced natural replenishment of the coastline.
Over the past century, the Mediterranean Sea has seen an average sea level rise of about 3.4 millimetres per year due to global warming. This leads to an additional substantial increase in coastal erosion and vulnerability to storm surges.
Based on satellite data, coastal erosion around Alexandria has been estimated at around 1 meter per year in certain areas. This rapid rate of erosion threatens infrastructure, coastal communities, and agricultural lands. Alexandria is Egypt’s second-largest city and home to over 5 million people. Many of the residents rely on agriculture, fisheries, and tourism, all of which are directly or indirectly affected by changes in the coastline. Therefore, Egypt combats coastal erosion around Alexandria and has, for example, spent 21 million Euro in 2018 for this task.
Exercises
- Based on the satellite images, estimate the maximum retreat of the coastline near the river mouth since 1985.
- Compare the satellite images and try to identify changes in the landuse. Focus on settlements, agricultural land and aquaculture.
